ed Peter and ____ of his two sisters,but none of them knew when their uncle came back

Do you know why the river was polluted? — Many different factors ___________ the serious pollution of the river.

If you keep working like this, your health will ________ under the pressure of work sooner or later.[ ]

still remember the first time you _______with a girl—Not exactly, but I remember it was a Sunday

I hear they’ve ____ Tom because of his performance, which he didn’t mention when we talked on the phone.